A 10-yr-old trial of Pinus pseudostrobus (1 provenance from Guatemala) and P. maximinoi (3 provenances from Guatemala, Honduras and Nicaragua) at the Pakhribas Agricultural Centre, East Nepal (1940 m altitude), was assessed in 1986 and given a first thinning in 1987. There was little difference between the species/provenances in survival (87-94%), growth (mean diameter at breast height (d.b.h.) 13.3-15.6 cm, mean height 8.85-9.23 m) and form, but all grew better than suppressed P. roxburghii planted at the same time (survival 94%; height 3.91 m); the latter species grows poorly at high altitudes. Mean standing volume before thinning was 138 m³/ha, and mean thinning volume yield (including live and dead suppressed trees) 41 m³/ha. Biomass production estimates were made using data from every 5th thinned tree and regression analyses made of dry weight (total above ground and by component) on d.b.h. A table is given for predicting dry weights from d.b.h. Total dry weight removed in thinning was 25.9 t/ha. All 4 species/provenances were coarse in form and branching and it is suggested that the indigenous P. wallichiana would be a better species to use (younger trees of this species growing nearby were growing vigorously).